“Space trash” and “space junk” are terms for the man-made litter that is floating in space or otherwise stuck there.
Much of it orbits Earth. We know the problem is real when we hear about the Orbital Debris Program Office of the National Aeronautics and Space Administration (NASA) at Johnson Space Center, Houston.
What all is whizzing around out there? By NASA’s accounting, the mess of it would fill a few junkyards if it were dumped in one place. Some 20 tons of stuff are stuck on the moon, like dead engines that can’t rust without free oxygen and water.
Other trash orbits Earth on paths set by its creation, traveling at speeds over 22,000 miles per hour. This junk includes spent rocket boosters, pieces that fall off spacecraft, and fragments and specks created by space collisions.
Certain trash has its own fame. There is the glove that floated away from Gemini 4 during the first U.S. spacewalk and the camera Michael Collins lost from Gemini 10. There are remains from space explosions.
Another stream of trash comes from man-made satellites. More than 4,000 satellites have been launched into Earth orbit. They came from over 50 countries and were launched from sites in 10 nations.
A few hundred of the thousands are currently useful. The rest are space trash.
Satellites are put in Earth orbit for many reasons. The most familiar uses are satellites for civilian and military observation of the Earth, for communications, navigation, weather data and research.
Satellite orbits vary greatly depending on their purpose and, in due time, a satellite’s fate depends on its orbit. Earth’s gravity pulls space trash to lower and lower orbits until it reaches the Earth’s atmosphere, where most of it burns up. The higher its initial orbit, the longer time before trash is pulled near enough to burn up.
Trash in orbits lower than 400 miles normally falls to Earth in a few years. Trash in orbits higher than 600 miles can keep circling Earth for a century. All the while new trash happens.
The trash now in space is estimated at hundreds of millions of pieces, ranging in size from as large as a truck to smaller than a flake of paint.
Space engineers worry about space trash, because it poses risks to what we do in space. Even a flake of paint going 22,000 miles an hour can and does damage spacecraft windows. Trash of four inches in size can penetrate most spacecraft. A four-inch chunk of whizzing trash can do the damage of 25 sticks of dynamite, says NASA.
Mother Nature was the first one to leave trash in space. More or less sand-size meteoroids speed through space and millions of them hit the Earth’s atmosphere every day.
Their brightest bold streaks across the night sky aroused chirps of joy and wonder before humans began writing. We know more now, but we still watch and wonder. The grains and pebbles add an estimated 1,000 tons of mass to Earth every day. Research on trash problems is grouped into five topics – modeling, measurements, protection, mitigation, and reentry. That is to say, NASA sizes up the effects and devises ways to minimize the damage and risk from junk in space.
Reentry is man’s twist on nature’s primordial treatment of space trash. The scheme is to get stuff back to the atmosphere quicker, where it can burn up or crash with no risk. Doing this may require loading extra fuel aboard a space vehicle.
There is much to learn about the life and times of space trash. So too for the dust, sand and pebbles that come to Earth from the ages.